1. Field of the Invention
The present invention relates to an orthogonal magnetoresistive (MR) head and more particularly to an orthogonal MR head which employs two terminals for conducting a sense current through an MR stripe and for transversely biasing the MR stripe.
2. Description of the Related Art
An orthogonal MR head includes an MR stripe sandwiched between first and second gap layers which in turn are sandwiched between first and second shield layers. The orthogonal MR head differs from the ordinary MR head in that the MR stripe extends perpendicular to its head surface, the head surface being the surface which faces a magnetic medium for sensing read signals. The orthogonal MR head has a first lead, connected to a bottom portion of the MR stripe, and a second lead, connected to a top portion of the MR stripe, the first lead and the bottom portion of the MR stripe forming a portion of the head surface.
The orthogonal MR head can be used alone or can be combined with a write head in an integrated write/read structure. Two such integrated structures are the "piggyback" head and the "merged" head. In the piggyback and merged heads, a write head is stacked on top of an MR read head. The merged head employs the second shield of the MR read head as a first pole piece for the write head. In contrast the piggyback head employs a separate layer for the first pole piece.
In a typical orthogonal MR head two terminals are employed for conducting a sense current through a pair of MR stripes. When the sense current flows, the MR stripes back bias each other with a magnetic field which induces a longitudinal bias. The use of two MR stripes to induce longitudinal bias inherently overbiases both of the MR stripes, causing them to be less sensitive to a read signal. In order to overcome this problem it has been proposed that only a single MR stripe be employed and that the MR stripe be longitudinally biased by track edge exchange or hard bias stabilization and transversely biased by a conductor which extends laterally across the MR stripe between its top and bottom portions. However, this configuration requires at least an extra terminal for the conductor. An extra terminal increases the size of the head and runs counter to the present day goal of minimizing head size and simplifying fabrication.
A problem is encountered in the construction of an integrated write/read head that includes an orthogonal MR transducer. It is difficult to form the second pole tip for the write head because of a nonplanar configuration of the layers which form the orthogonal MR transducer. This nonplanar configuration is caused by the contour of the first lead across the bottom portion of the MR stripe. Still another problem of the orthogonal MR head is shorting between the second lead and either of the first and second shield layers at the head surface. This is caused by smearing of the conductive material of the first and second shields during lapping to form the head surface.